Determining the Solubility Product of Fe(OH)3: An Equilibrium Study with Environmental SignificanceMichelle Meighan, Joseph MacNeil, and Renee FalconerThis study explores the environmental impact of acidic mine drainage by investigating the relationship between pH and the aqueous solubility of heavy metals. Students precipitate Fe(OH)3 from acidic FeCl3 and NaOH and use the concentrations of ferric and hydroxide ionsdetermined through pH and flame spectroscopyto calculate the Ksp of Fe(OH)3.Meighan, Michelle; MacNeil, Joseph; Falconer, Renee. J. Chem. Educ.2008, 85, 254.

Acids / Bases |

Aqueous Solution Chemistry |

Equilibrium |

Precipitation / Solubility |

Spectroscopy

The Use of Limits in an Advanced Placement Chemistry CoursePaul S. Matsumoto, Jonathan Ring, and Jia Li (Lily) ZhuThis article describes the use of limits in topics usually covered in advanced placement or first-year college chemistry. This approach supplements the interpretation of the graph of an equation since it is usually easier to evaluate the limit of a function than to generate its graph.Matsumoto, Paul S.; Ring, Jonathan; Zhu, Jia Li (Lily). J. Chem. Educ.2007, 84, 1655.

Acids / Bases |

Equilibrium |

Gases |

Mathematics / Symbolic Mathematics |

Thermodynamics

Peer-Developed and Peer-Led Labs in General ChemistryLorena Tribe and Kim KostkaDescribes a student-developed and led laboratory curriculum as a model for producing a more student-centered and rich laboratory experience in general chemistry laboratories.Tribe, Lorena; Kostka, Kim. J. Chem. Educ.2007, 84, 1031.

Equilibrium Constants and Water Activity RevisitedDavid KeeportsSubtle arguments based upon the use of chemical potentials show that numerical values of solute molar concentrations can be used as good approximate activities in equilibrium calculations for reactions involving dilute solutions.Keeports, David. J. Chem. Educ.2006, 83, 1290.

Equilibrium Constants and Water ActivityDavid KeeportsGeneral chemistry instructors are faced with a dilemma when introducing the topic of equilibrium constants: These constants are correctly written in terms of activities, yet activity is a complex topic better treated rigorously in a physical chemistry course than superficially in a general chemistry course. Thus, to introduce equilibrium calculations, it is necessary to use approximate forms for equilibrium constants. However, I find that some commonly used textbooks provide incorrect arguments leading to approximate equilibrium constants for aqueous reactions.Keeports, David. J. Chem. Educ.2005, 82, 999.

Acids / Bases |

Aqueous Solution Chemistry |

Equilibrium |

Water / Water Chemistry

Analysis of Natural Buffer Systems and the Impact of Acid Rain. An Environmental Project for First-Year Chemistry StudentsDavid C. Powers, Andrew T. Higgs, Matt L. Obley, Phyllis A. Leber, Kenneth R. Hess, and Claude H. YoderThe purpose of this project is to investigate the basic principles involved in acidbase buffer systems within the context of an environmental issue. It is designed for use in an introductory chemistry course. The students will learn about acidbase interactions and examine how a buffer system composed of a weak acid and its conjugate base can neutralize large quantities of strong acid while resisting drastic change in the pH of the system. Students will also analyze experimentally the various components of the most commonly occurring natural buffer system.Powers, David C.; Higgs, Andrew T.; Obley, Matt L.; Leber, Phyllis A.; Hess, Kenneth R.; Yoder, Claude H. J. Chem. Educ.2005, 82, 274.

Acids / Bases |

Aqueous Solution Chemistry |

Equilibrium

Using Clinical Cases To Teach General ChemistryBrahmadeo Dewprashad, Charles Kosky, Geraldine S. Vaz, and Charlotte L. MartinThis article describes how a fact-based clinical case was effectively used to motivate and enrich the classroom experience and review many of the concepts covered in general chemistry. The case involves an elderly patient who was brought to the emergency room. The results of his physical examination and laboratory analysis of his blood are presented. The students, in peer-led groups, work through the chemical principles involved in the doctor's diagnosis and treatment options for the patient. The article describes the case study, instructors' observations, and students' perception of the activity. Dewprashad, Brahmadeo; Kosky, Charles; Vaz, Geraldine S.; Martin, Charlotte L. J. Chem. Educ.2004, 81, 1471.

Acids / Bases |

Drugs / Pharmaceuticals |

Equilibrium |

Kinetics |

Medicinal Chemistry

Unified Approximations: A New Approach for Monoprotic Weak Acid–Base EquilibriaHarry L. Pardue, Ihab N. Odeh, and Teweldemedhin M. TesfaiThis article describes a new approach to approximate calculations for monoprotic acidbase equilibria in otherwise pure water. The new approach, identified herein as unified approximations, uses a simple decision criterion to select between situations that should be treated as deprotonation and protonation reactions. The remaining treatment takes account of changes in concentrations of conjugate acidbase pairs for all situations and ignores autoprotolysis only for situations for which the analytical concentration of either the conjugate acid or conjugate base will always be larger than zero. Pardue, Harry L.; Odeh, Ihab N.; Tesfai, Teweldemedhin M. J. Chem. Educ.2004, 81, 1367.

Acids / Bases |

Equilibrium |

Chemometrics

The Relative Acidities of Water and MethanolHenry I. AbrashAnalysis of the disparity between the way the acidity constant of water is presented in general chemistry and organic chemistry textbooks.Abrash, Henry I. J. Chem. Educ.2001, 78, 1496.

Modification of Small-Scale One-Pot Reactions to an Inquiry-Based Laboratory ExerciseC. Jayne WilcoxStudents are given an initial handout and asked to complete a short, attention-getting exercise. They must continue to work on logical, short exercises given to them one at a time, in handout format. The inquiry-based approach is intended to increase students' comprehension of what they're doing in the laboratory and why.Wilcox, C. Jayne. J. Chem. Educ.2001, 78, 62.

Acids / Bases |

Aqueous Solution Chemistry |

Precipitation / Solubility |

Equilibrium

Every Year Begins a MillenniumJerry A. BellThis article outlines a series of demonstrations and their contexts, leading to recommendations about what we teach and how we teach.Bell, Jerry A. J. Chem. Educ.2000, 77, 1098.

Acids / Bases |

Aqueous Solution Chemistry |

Equilibrium |

Kinetics |

Learning Theories

An Acid-Base Chemistry Example: Conversion of NicotineJohn H. SummerfieldThe current government interest in nicotine conversion by cigarette companies provides an example of acid-base chemistry that can be explained to students in the second semester of general chemistry.Summerfield, John H. J. Chem. Educ.1999, 76, 1397.

Acids / Bases |

Drugs / Pharmaceuticals |

Equilibrium

Predicting Acid-Base Titration Curves without CalculationsDennis W. BarnumIn this paper a qualitative and systematic method for sketching titration curves is presented. Even the more complex cases such as salts or polyprotic acids and bases are treated just as easily as simple monoprotic acids. Having students predict the shape of titration curves from known equilibrium constants helps to focus attention on the general principles without distraction by the mathematics. Barnum, Dennis W. J. Chem. Educ.1999, 76, 938.

Acids / Bases |

Quantitative Analysis |

Water / Water Chemistry |

Equilibrium |

Learning Theories |

Titration / Volumetric Analysis |

Chemometrics

Do pH in Your HeadAddison AultEvery aqueous solution has a pH. Two factors determine this pH: the acidic or basic strength of the solute, and its concentration. When you use pKa values to express acidic and basic strength you can easily estimate the approximate pH of many aqueous solutions of acids, bases, and their salts and their buffers.Ault, Addison. J. Chem. Educ.1999, 76, 936.

Equilibrium |

Acids / Bases |

Aqueous Solution Chemistry |

Learning Theories |

Chemometrics |

Brønsted-Lowry Acids / Bases

Why Not Replace pH and pOH by Just One Real Acidity Grade, AG?Henk van LubeckThe disadvantages of pH and pOH disappear after replacing them with AG, the acidity grade: AG = log [H+]/[OH-]. AG of neutral solutions equals 0 at all temperatures, whereas AG of acidic solutions is positive and of alkaline solutions, negative. AG offers some other minor advantages as well. van Lubeck, Henk. J. Chem. Educ.1999, 76, 892.

Why and How To Teach Acid-Base Reactions without EquilibriumTerry S. CarltonA stepwise method enables students to predict which acid-base reactions occur when two solutions are mixed. The complexities of equilibrium are avoided by treating reactions as all-or-none and by providing a table of acids in order of strength. Carlton, Terry S. J. Chem. Educ.1997, 74, 939.

Visible Ion Exchange Demonstration for Large or Small Lecture HallsJerry A. DriscollThis article presents a very simple experiment involving the sense of smell that students can accomplish during lecture. This classroom exercise involves very little preparation time and can be used to illustrate the important concepts of equilibrium along with acid/base properties of various ions.Driscoll, Jerry A. J. Chem. Educ.1996, 73, 639.

Teaching the Truth about pHHawkes, Stephen J.-log[H+] is only an approximation to pH; how to teach pH to avoid misleading students.Hawkes, Stephen J. J. Chem. Educ.1994, 71, 747.

pH |

Acids / Bases |

Aqueous Solution Chemistry |

Equilibrium

Fruit Anthocyanins: Colorful Sensors of Molecular MilieuCurtright, Robert D.; Rynearson, James A .; Markwell, JohnProvides background and references as a starting point for the further exploration of anthocyanins.Curtright, Robert D.; Rynearson, James A .; Markwell, John J. Chem. Educ.1994, 71, 682.

General treatment of aqueous ionic equilibria using predominance diagramsVale, J.; Fernandez-Pereira, C.; Alcalde, M.This paper illustrates the advantage of a unified instructional treatment based on the similarities o equilibria between acid-base and oxidation-reduction reactions that could be used in a general chemistry course.Vale, J.; Fernandez-Pereira, C.; Alcalde, M. J. Chem. Educ.1993, 70, 790.

The acid equilibrium constant is unity!Baldwin, W. G.; Burchill, C. E.The attempt to assign a non-unity value to this equilibrium constant is a consequence of misunderstanding the way in which the (nearly) constant concentration or activity of the solvent in a dilute solution (or of a pure solid or liquid in a heterogeneous system) is treated when formulating the conventional equilibrium constant expression.Baldwin, W. G.; Burchill, C. E. J. Chem. Educ.1992, 69, 514.

Chemical equilibrium: III. A few math tricks Gordus, Adon A.The third article in a series on chemical equilibrium that considers a few math "tricks" useful in equilibrium calculations and approximations.Gordus, Adon A. J. Chem. Educ.1991, 68, 291.

The perils of carbonic acid and equilibrium constantsJencks, William P.; Altura, Rachel A.It is important to remember that the small amounts of carbon dioxide that are usually present in water can have large effects on acid-base equilibria of dilute solutions and that dilute solutions of most weak acids and bases undergo significant protonation or hydrolysis when they are dissolved in water.Jencks, William P.; Altura, Rachel A. J. Chem. Educ.1988, 65, 770.

Acids / Bases |

Equilibrium |

Aqueous Solution Chemistry

Potentiometric titration of acidic and basic compounds in household cleanersLieu, Van T.; Kalbus, Gene E.The potentiometric titration of commercial household cleaners can be used in student laboratories in freshman, analytical, and physical chemistry courses. It can be used for analysis of household cleaners with either one or two component systems, or it can be used for the determination of the dissociation constant.Lieu, Van T.; Kalbus, Gene E. J. Chem. Educ.1988, 65, 184.

Why teach solution equilibrium?Butler, James N.What are the most important aspects of solution equilibrium to teach at the elementary level?Butler, James N. J. Chem. Educ.1984, 61, 784.

Equilibrium |

Solutions / Solvents |

Acids / Bases |

pH

Cooking with chemistryGrosser, Arthur E.Two demonstrations involving cooking eggs and suggestions for many more examples of cooking that illustrate important principles of chemistry. From the "State-of-the-Art Symposium for Chemical Educators: Chemistry of the Food Cycle".Grosser, Arthur E. J. Chem. Educ.1984, 61, 362.

"To sink or swim"O'Connor, RodA problem regarding the maximum water hardness that can be permitted in a swimming pool if it is desired to avoid calcite formation given the carbonate ion concentration. [Debut]O'Connor, Rod J. Chem. Educ.1980, 57, 151.

Acids / Bases |

Aqueous Solution Chemistry |

Equilibrium |

Solutions / Solvents

Strong and weak acids and basesDeck, Joseph C.The designations "strong" and "weak" are used in various ways, and often with respect to the same compound in different situations.Deck, Joseph C. J. Chem. Educ.1979, 56, 814.

Acids / Bases |

Equilibrium |

Aqueous Solution Chemistry

Intuitive and general approach to acid-base equilibrium calculationsFelty, Wayne L.The purpose of this paper is to show that the usual intuitive approach used in general chemistry can be readily extended without introduction of additional, sophisticated concepts to give the general, exact expression and to point out the pedagogical advantage of its use.Felty, Wayne L. J. Chem. Educ.1978, 55, 576.

Effect of Ionic Strength on Equilibrium ConstantsSeymour, M. D.; Fernando, QuintusInvolves the determination of the acid dissociation constant of bromcresol green by a spectrophotometric method; using a graphing calculator, each student can perform the laboratory work and obtain his own data set.Seymour, M. D.; Fernando, Quintus J. Chem. Educ.1977, 54, 225.

MiscellaneousAlyea, Hubert N.These twelve overhead projection demonstrations include rates of reactions, clock reactions, the effect of temperature and the presence of a catalyst on the decomposition of hydrogen peroxide, the relationship between viscosity and temperature, equilibria, solubility product, and the common ion effect.Alyea, Hubert N. J. Chem. Educ.1970, 47, A437.

Teaching ionic equilibrium: Use of log chart transparenciesFreiser, Henry; Fernando, QuintusThe use of graphical methods brings the problem of significance of various terms in complicated expressions into proper focus. Furthermore, a pictorial representation permits the student to see at a glance how the concentrations of various species in a system at equilibrium change with conditions.Freiser, Henry; Fernando, Quintus J. Chem. Educ.1965, 42, 35.

Equilibria in ionic solutionsKokes, R. J.; Dorfman, M. K.; Mathia, T.In conjunction with lectures on equilibria in electrolytic solutions, students perform a set of laboratory experiments in which they determine both the ionization constant of chloroacetic acid and the solubility of its silver salt.Kokes, R. J.; Dorfman, M. K.; Mathia, T. J. Chem. Educ.1962, 39, 93.

Equilibrium |

Aqueous Solution Chemistry |

Acids / Bases |

Precipitation / Solubility

An approach to complex equilibrium problemsButler, James N.Presents an approach to equilibrium problems that sets up enough equations relating the various concentrations present to define the system completely and then makes approximations that simplify the equations.Butler, James N. J. Chem. Educ.1961, 38, 141.

Equilibrium |

Chemometrics |

Acids / Bases |

Aqueous Solution Chemistry

Potentiometric measurements of equilibria: In general chemistry laboratoryChesick, J. P.; Patterson, Andrew, Jr.The authors describe an experiment in which the solubility product of silver chloride, the ionization constant of the silver-ammonia complex, and the ionization constant of acetic acid can be determined with one afternoon of work.Chesick, J. P.; Patterson, Andrew, Jr. J. Chem. Educ.1959, 36, 496.